The blood reaches from the top of your body to the bottom. Vice versa it has to reach from the bottom of your body back to the top. How does your body defy gravity and flow upwards? Well these were the questions I had sitting in lecture listening to my professor go on and on about the hearts job.
Well, Your heart circulates blood 1000 times each day. Arteries, arterioles, capillaries, venules, and veins are the 5 types of blood vessels that help this process along. The arteries carry blood away from the heart, the arterioles are smaller vessels that branch out from the arteries, the arterioles branch into smaller vessels called capillaries, capillaries unite to form small vessels called venules, and venules join together to form larger vessels called veins which carry blood to the heart.
So the arteries are high pressure vessels which can exceed the forces of gravity and cause blood to circulate into tissues above the heart. Also, valves in the venules and veins make the system a one-way loop and prevent the backflow of blood. This is how your heart fights against gravity. I think that are bodies are wonderfully made and every part has a specific function that helps to keep us alive and working properly. The heart is a beautiful design!
Image credit:
http://firststatevein.com/images/veins-and-arteries.png
